This invention relates to an image display apparatus for a liquid crystal television receiver using a liquid crystal display panel.
Recently, portable liquid crystal television receivers using a liquid crystal display panel have been replacing CRTs in practical use. In Japanese television broadcasting the NTSC system is adopted. In the NTSC system, one vertical scanning period or one field has 262.5 horizontal scanning lines. On the other hand, a liquid crystal display panel having 120 by 160 picture elements has 120 scanning side electrodes, which correspond in number to substantially one half the number of effective horizontal scanning lines in one field of the video signal in the prior art. This means that the scanning side electrodes are driven for display each for every two horizontal scanning periods. In a liquid crystal television receiver using a liquid crystal display panel, one back plate period for a liquid crystal display panel corresponds to two horizontal scanning periods in the video signal. With the prior art liquid crystal television receiver, a video signal for only one horizontal scanning period is sampled during one back plate period, i.e., the sampled data is used for display for one back plate period. That is, with the prior art liquid crystal television receiver only substantially one half of the video signal of the ordinary television receiver can be obtained in the same horizontal scanning period. Therefore, even if the sampled video signal for a horizontal scanning period contains noise, it is displayed as such for one back plate period. In addition, even if adjacent video signals in one back plate period are considerably different, only one of them is used, leading to deterioration of the image display quality.
Further, in a prior art liquid crystal television receiver where signal electrode side register and driver circuit have n-bit structures, an n-bit television signal is received for display in 2.sup.n gradations. Therefore, if the number of bits is insufficient, the number of gradations is also insufficient, so that fine intermediate tones of color cannot be sufficiently displayed. To increase the number of gradations, it is necessary to increase the number of bits, thus leading to complication of the circuit construction.